This invention relates generally to a method and system for improving combustion. More particularly, this invention relates to a method utilizing a deoxygenating device for removing dissolved oxygen to enable fuel preheating for improved combustion performance.
An energy conversion device that utilizes a liquid hydrocarbon fuel can benefit from pre-heating fuel prior to the combustion process. Increasing fuel temperature improves fuel atomization and vaporization characteristics by reducing the time required to vaporize the fuel. Reduced vaporization times can potentially provide reductions in mixing and combustion times. Improved mixing and vaporization of fuel prior to combustion can improve combustion efficiency and flame stabilization, as well as reduce the emission of nitrogen oxides, carbon monoxide, unburned hydrocarbons, and particulates. Further, heating the fuel can favorably alter the composition of fuel by initiating desirable cracking reactions. These are all examples of the impact and advantages that pre-heating of a hydrocarbon fuel can have on a combustion process.
Disadvantageously, the temperature at which a hydrocarbon fuel may be heated is limited by the formation of insoluble products referred to as “coke”. Formation of such insoluble products occurs when oxygen containing hydrocarbon fuel is heated beyond a certain temperature, such as, for examples above 350° F. Such insoluble products can potentially undesirably affect portions of a fuel system. The formation of coke deposits is dependent on the amount of dissolved oxygen present within the fuel due to prior exposure to air. The generation of insoluble products in a fuel due to dissolved oxygen has thus far prevented pre-heating of fuel to levels that desirably improve the combustion process.
Removing dissolved oxygen from a hydrocarbon fuel is known to substantially decrease the formation of undesirable insoluble products. U.S. Pat. Nos. 6,315,815 and 6,709,492 assigned to Applicant disclose devices for removing dissolved oxygen using a gas-permeable membrane. As fuel passes along the permeable membrane, oxygen molecules in the fuel diffuse out of the fuel across the gas-permeable membrane. An oxygen partial pressure differential across the permeable membrane drives oxygen from the fuel, which is unaffected and passes over the membrane.
Accordingly, it is desirable to develop a method and system for improving a combustion process that removes dissolved oxygen from the fuel providing for pre-heating of fuel to temperatures that desirably improve combustion.